riscv pending interrupts freezes the kernel, fixing by csr_clear-call

[Mikko Saari]

Hello Linux! In earlier Linux Risc-V-patches (ultraembedded 4.20-kernel) 
there was interrupt handling implemented by following way in 
"linux/arch/riscv/kernel/irq.c".
-----------------------------------------------------------------------------kernel 
4.20
 case INTERRUPT_CAUSE_EXTERNAL:
#ifdef CONFIG_XILINX_INTC
                {
                     unsigned int irq;
                        irq = xintc_get_irq();
                next_irq:
                        BUG_ON(!irq);
                        generic_handle_irq(irq);

                        irq = xintc_get_irq();
                        if (irq != -1U) {
                pr_debug("next irq: %d\n", irq);
                goto next_irq;
            }
        }
                csr_clear(sip, 1 << INTERRUPT_CAUSE_EXTERNAL);
#else
             handle_arch_irq(regs);
#endif
              break;
    default:
                panic("unexpected interrupt cause");
-------------------------------------------------------------------------------

  However, in current Linux version (6.5) there is no corresponding   
csr_clear(sip, 1 << INTERRUPT_CAUSE_EXTERNAL)-call anywhere, at least I 
haven't been able to find it.
Instead I did a "quick and dirty" -fix to the file 
"linux/drivers/irqchip/irq-xilinx-intc.c" and put the corresponding 
call     csr_clear(CSR_SIP, IE_EIE);
to function
------------------------------------------------------------------------kernel 
6.5
 static void xil_intc_irq_handler(struct irq_desc *desc)
{
    struct irq_chip *chip = irq_desc_get_chip(desc);
    struct xintc_irq_chip *irqc;
    u32 pending;


    irqc = irq_data_get_irq_handler_data(&desc->irq_data);
    chained_irq_enter(chip, desc);
    do {
        pending = xintc_get_irq_local(irqc);
        if (pending == 0)
            break;
        generic_handle_irq(pending);
    } while (true);
    chained_irq_exit(chip, desc);
    csr_clear(CSR_SIP, IE_EIE);
}
---------------------------------------------------------------------------
Now the interrupts are not pending and the system is not halted as it 
was before for example while using spidevtest before the modifications. 
The call csr_clear() clears pending interrupts that would otherwise halt 
the Linux kernel.
I wonder if this should be fixed somehow more elegantly? I am grateful 
for any answers. I am just a beginner in the adventure of the driver 
development, and any sensible answer is real help :)
Best Regards, Mikko Saari